The investigators have shown that the venom of the Eastern green mamba from Africa, Dendroaspis angusticeps, is an excellent source for toxins that distinguish the m1 and m4 subtypes of muscarinic receptors, and have preliminary evidence for the presence of toxins specific for m2 receptors. The anti-muscarinic and toxins are present only in trace amounts. They therefore hypothesize that the toxins of most interest can be best identified by a combination of protein purification and recombinant DNA approaches, and obtained most easily in useful quantities by expression of the corresponding cDNA clones.